Control for a matrix printing assembly

ABSTRACT

A control for a matrix printing assembly to determine the character and spacing thereof in a data terminal comprising the combination of a mechanical linear strobe and an electronic timing circuit accurately controlling and positioning the stroke of each rod or stylus of the matrix printer.

United States Patent 1 1 1111 3,838,250

Naas et al. Sept. 24, 1974 CONTROL FOR A MATRIX PRINTING 3,356,02112/1967 May et al. 235/619 R ASSEMBLY 23328 2/1332]; Perkins et a].197/187 Inventors: g g f- N f g gm la g 3:703:94) 11/1972 Howard etal.197/19 u eran; ae esl, 0 f8 kl 11 f l'f. o e ey a 0 Cal PrimaryExaminerStuart N. Hecker Asslgneer The Smger p y, New York, Attorney,Agent, or Firm-E. L. Bell; 1. R. Dwyer; A.

W. Kozak [22] Filed: Jan. 5, 1973 [21] Appl. N0.: 321,177 57 ABSTRACT Acontrol for a matrix printing assembly to determine 235/61'9 197/187 thecharacter and spacing thereof in a data terminal [581 d 9 comprising thecombination of a mechanical linear le 0 earc 5/6] 6 1 9 strobe and anelectronic timing circuit accurately controlling and positioning thestroke of each rod or sty- [56] References Cited lus of the matrixprinter.

UNITED STATES PATENTS Allen 197/19 15 Claims, 10 Drawing FiguresPmamanww 3.838.250

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CONTROL FOR A MATRIX PRINTING ASSEMBLY CROSS-REFERENCES TO RELATEDAPPLICATIONS US. application entitled A data Terminal With DualThree-Station Printing" of Howard R. Cederberg and Charles W. Wiedeman,filed Jan. 5, 1973 as Ser. No. 321,176; and U.S. application entitled AnAssembly for Spooling an Audit Trail in a Data Terminal of James G.Savage and Arnold L. Hawkins, filed Jan. 5, 1973, as Ser. No. 321,196.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates in general to the means for positioning and controlling a matrixtype printer and is particularly directed to the means of positioningand controlling a matrix printer in data terminals commonly known aselectronic cash registers.

2. Description of the Prior Art Conventional matrix printers have aplurality of wires, each individually moved by a magnetic actuator,usually against a return spring, to impact a record medium to print acharacter, one wire imprinting one spot or dot of the character at atime. Such matrix printers use either seven or 35 such wires positionedin aligned configuration at the point of impact and are individually andsequentially strobed so as to print the character.

Heretofore, the strobing of each wire, the positioning of the entirecharacter on the media, and the spacing between characters to form linesand columns of printed matter have been effected by electroniccircuitry, usually timing devices or counters of some type.Unfortunately, however, experience has shown that reliance uponelectronic circuitry, alone, has not been satisfactory and skewing ofthe printed characters, especially columns of printed matter, hasresulted.

SUMMARY OF THE INVENTION This invention combines the mechanical andelectronic aspects of a linear strobe bar and electronic circuitrycooperating in combination to precisely position and print characters ona record media for a point-ofsale data terminal. The linear strobe bar,accurately positioned on the data terminal, contains a plurality ofslots of a selected size and location which cooperate with sensingdevices movable with the matrix printer of the data terminal so that asthe printer moves transverse the recording media, the sensing devices,according to the selected slot and required character, enable theelectronic circuitry to strobe the wires of the matrix printers to printthe character as required by the input to the data terminal. Thecircuitry and slots on the mechanical strobe bar are designed to providea correct spacing of the characters for the appropriate rows and columnsto be printed on the record media as the latters drive incrementallymoves the media in the data terminal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of aportion of a data terminal skeletonized and with the cover removed toillustrate the carriage for the matrix printers with the linear strobebar positioned to position and control the spacing of the characters inrows and columns on the record media;

FIG. 2 is a schematized exploded view of the sensing devices mounted tomove with the carriage relative to the linear strobe bar;

FIG. 3A is a plan view of the strobe bar enlarged as compared to FIG. 2to show the details thereof;

FIG. 3B is a timing diagram for each of the light sensors in relation tothe linear strobe bar channels;

FIG. 4 is a schematic spacing and timing sketch illustrating the 9 X 7printing matrix and nonprint space.

FIGS. 5A and 5B are simplified block diagrams of the electroniccircuitry which coordinates with the linear strobe bar and enables theprintout on paper media regardless of direction of carriage motion.

FIGS. 6A, 6B, and 6C illustrate various logic and timing functions ofthe system.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the data terminal 10(with cover removed for purposes of clarity) is shown as comprising,overall, a carriage l2 movable laterally with respect to a frame 14, awork level surface 16 having three print stations 18, 20 and 22, and anappropriate keyboard 24. The three print stations 18, 20 and 22 are,respectively, a receipt station where the customers receipt is printed(if a receipt is required), an audit station where the storekeepersrecord (audit trail) of all transactions are printed, and a form stationwhere the customers order form or bill of sale is printed, if required.

By this arrangement, the carriage 12, will move, not only from theprinting position shown, viz., at the audit station and receipt station,but to the form station and audit station as well as traversing eachpair of stations so that appropriate rows and columns of data enteredinto the data terminal at the keyboard 24 is appropriately printed out.The carriage 12 is mounted on a pair of bars 26 and 28 to hold thecarriage in parallel relationship with the platen 16 and the rest of thedata terminal and transverse movement on the parallel bars isaccomplished by a suitable drive mechanism 30 including a belt 32,attached to carriage 12, and pulley means 34 motivated by a reversiblemotor (not shown).

In the embodiment shown, a receipt 36, if required, is printed in thereceipt station 18 and an audit trail 38 is printed in the audit station20 when the carriage 12 is in the position shown as the two record media(paper) are moved forward, i.e., in thhe direction of the keyboard 24,and forms a suitable supply, such as a roll of paper, by a suitableroller feed mechanism 40 driven by a motor and clutch means 42 coupledto shaft 44. When the carriage 12 is positioned to the left from thatshown, a form 46, such as a customer order form or bill of sale, isprinted in station 22 at the same time the audit trail 38 is beingprinted.

The audit trail 38 is rolled onto a spool 48 partially shown in FIG. 1,while the receipt 36 is severed, when a complete transaction isrecorded, by a suitable cutting mechanism, indicated in its entirety as49. Also, the forms station is provided with a pair of electronicsensing means 50 and 52 which determine when a form 46 is properlylocated in the forms station, otherwise the terminal is inhibited fromoperating; suitable electronics being provided for this purpose. Rollers54 feed the form in a direction opposite from the direction of travel ofthe audit trail by suitable gearing to couple the rollers to shaft 42which moves the form and audit trail or audit trail and receipt, or anaudit trail alone, as the case may be, incrementally, in response to andin combination with printing mechanisms to form rows and columns of dataas determined by the input to the keyboard 24.

The carriage 12 is also provided with a pair of matrix printers 56 and58 capable of printing on two of the three stations at the same time,viz., the receipt station and the audit station, or (when the carriageis positioned to the left from that shown) on the form station and auditstation.

Suitable ink supply means for the dual matrix printer are located in thecarriage and are shown in FIG. 1 only schematically, since the ribbon,its novel inking supply arrangement and other details to improve theoperation of the matrix printers and data terminals generally aredescribed and claimed in a copending application. It should beremembered that the matrix printers 56 and 58 are capable of printing anaudit trail and 'a receipt, an audit trail alone or on a form, an audittrail depending upon the mode determined in the keyboard 24. The properpositioning and printing of the characters in rows and columns isdependent upon the combination of a mechanical strobe means 60 andelectronic circuitry which cooperates therewith and it is thiscombination that will be described in detail hereinafter.

It should be noted at this time, however, that one of the manyadvantages of matrix printers in the data terminal is the ability toprint legibly through several copies of forms in the form station and,also, by suitable electronics described and claimed in the thisapplication, supra, the printing on the receipt is upside down relativeto the printing on the audit trail and form. This upside down printingon the receipt enables the complete transaction, such as a sale, to berecorded and totaled in the manner in which any transaction is normallyread, i.e., top to bottom, for the benefit of the customer. This is alsotrue of the form printed at the form station since the form moves in adirection opposite to the direction of travel of the receipt. This isnot true, however, for the printing on the audit trail, which is storedin the machine to be used by the vendor.

As will be seen in FIG. 1, the mechanical positioning means in theembodiment shown is the linear strobe mask or bar 60 which is affixed tothe frame 14 of the data terminal and is further illustrated in FIG. 3Ain a much enlarged form over that shown in FIG. 1 for purposes ofclarity. The linear strobe 60 comprises a relatively thin, long, flatplate containing a plurality of apertures for slots through whichsensing device such as phototransistors, LED's (light emitting diodes)or the like are provided to detect the absence or presence of a slot oraperture as the carriage 12 moves back and forth across the carriagebars carrying the sensing device along with it.

Referring to FIG. 3A, it will be seen that the linear strobe bar 60 ismade of three horizontal areas or channels of slots or apertures. Thetopmost channel, channel C, has a long slot 61, at the center and a longslot 62, at the right. The middle channel, channel B, has long slots63,, at the left and 64,, at the center. The lowermost channel, channelA, has a slot 65,, at the left, a slot 67,, in the center, and a slot69,, at the right. Between 65,, and 67,, there is a series of smallslots 66,, which comprise 32 equally spaced slots. A similar series of32 slots which are designated 68,, also appear between the larger slots67,, and 69,, of channel A.

Referring to FIG. 2, it will be seen that the carriage 12 carries withit a group of sensing devices 102, 104, 106, and 102', 104', and 106which comprise a group of light emitters and light sensors which arealigned with the channels A, B, and C of the linear strobe bar 60. Asthe carriage moves to the left and right along the linear strobe bar 60,the attached light sensing devices 102, 104, 106 and 102, 104', and 106'will convey a group of signals depending upon the location of thecarriage along the linear strobe bar 60. Thus, a means has been providedby which the carriage position in relationship to the linear strobe barmay be determined at any given time.

Certain indexing or HOME positions have been provided and these havebeen designated as the left- HOME position 70, the mid-HOME position 72,and the right-HOME position 74 which are used to provide certainindexing and other information when the dual matrix head carriage islocated in one of these three positions.

Between the left and mid HOME positions and 7 2, there is a left printfield 71 which allows space for the printing of 30 characters or spaces.Likewise, between the mid-HOME position 72 and the right-HOME position74, there is provided a print field-right 73 which provides for spacespermitting the printing of 30 characters or spaces.

Referring to FIG. 3B, which illustrates the resultant effect of themotion of the sensing devices of the carriage as they move across thelinear strobe bar 60, it will be seen that as the light sensors 102 and102' traverse the linear strobe 60 from left to right, then channel Cwill show that there is no positive or photosensitive output on channelC except for the area of the mid position and the area of the right HOMEposition 72 and 74.

Likewise, referring to the situation in regard to channel B where thesensing emitters and sensors 104 and 104' traverse this channel, it willbe seen from FIG. 3B that channel B is in the On or photosensitiveposition at the left-HOME position 70, after which it turns off until itreaches the mid-HOME position 72 and again turns off and remains in anormal Off" position.

In regard to channel A of the linear strobe bar 60 which is scanned bysensing emitters and receivers 106 and 106', it will be seen that thelight sensing devices are On for a portion of the left-HOME positionafter which they are turned off until they are again turned On at aportion of the mid-HOME position 72 and then remain off until they areagain turned On" at the portion of the strobe bar at the right-HOMEposition 74.

As a resultof the combination of these events of carriage motion inrelationship to the linear probe bar 60, it will be seen that certaindefinitions can be made from the condition of the light sensing devices,namely, that of the left HOME being defined as channel A on, channel Bon, and channel, C off; the mid-HOME can be defined as all channels Aand B and C, being on;" and the right-HOME can be defined as channel Aon, channel C on, and channel B off; further, the print field can bedesignated as the situation where both channel B is off and channel C isoff, while the strobe slots 66,, or 68,, provide strobe on pulses as thecarriage and sensors move transversely.

As will be seen in FIG. 3B in regard to channel A, the 32 small slots66,, (print field 71) or the 32 slots of 68,, (print field 73) willcause a series of sharp on/off pulses to occur along specified portionsof channel A. These pulses are called character strobe pulses andprovide as follows: when channel B is off and channel C is off, butchannel A comes On, then there occurs the initiation of a space and timeperiod which will permit the printing of an individual character, aswill later be seen in connection with FIG. 4.

Thus, there has been provided a dual matrix head assembly mounted on acarriage positioned to move left and right across the face of a linearstrobe bar. Light sensing means attached to the carriage and working inconjunction with the slots and apertures provided in the linear strobebar provide sensing signals which tell the electronic circuitry theposition of the carriage the areas in which the carriage may stop, andthe time and space positions in which it is permissible to print data onthe printout paper media.

In order to better understand the requirements of the electroniccircuitry in relationship to the printing mechanism, it should beunderstood that each of the dual matrix heads are composed of seven wirerods or styli which can be actuated electromagnetically by means ofoutput signals from a latch circuit 93 (FIG. 5).

The arrangement of the printable character head is such as that may bedescribed as a nine by seven (9 X 7) matrix. As will be seen in FIG. 4,there is shown a matrix arrangement whereby there is pictured sevenrows, each of which are spaced or separated by a distance L. Further,the matrix then further consists of nine columns which are separated byspaces equal to L/2; thus, there is provided a matrix of seven rows eachseparated by a space L and a series of nine columns, each separated by aspace L/2 so as to provide the capability of the matrix dot printerwhich is programmed to print numerals and/or letters and having thecapability of simulating curved areas.

Referring to FIG. 4, the space allowable for a single individualcharacter comprises 14 columns of which the first 9 columns are used forprinting the wire matrix heads while the remaining 5 columns constitutea noprint area to provide spacing between individual characters.

The strobe pulses derived from the slots 66,, or 68,, (of FIG. 3A) areused to electronically define the start and finish of each individualcharacter space. The trailing edge of the strobe pulse (FIG. 4) is usedto signal the end of one character space and the beginning of the nextcharacter space.

As will be discussed later, two alternate timing signals (15,, and qb(FIG. 4) are used to alternately enable" the activation of the firstmatrix head printer group and the second matrix head printer groupduring each individual column count of the first nine (print) columns.

Thus, there is the requirement for information to be delivered to theseven wires of each of the two matrix heads as to whether or not theyshould activate to imprint a dot pattern or not at any given position ofthe nine columns involved. Further, since there are nine sequentiallyprinted columns involved in the format of which column of a givencharacter matrix is available for printing and which of the seven-wirematrix heads are to be activated for that particular one column of thenine columns that constitute the character matrix.

As was previously discussed in FIG. 3A, the left print field 71 and theright field 73 of sections of the linear strobe bar are provided withthirty-two slots or apertures, each for purposes of locating the spacesand columns under which the printing of each individual character willtake place on one or more of the record media. As was heretoforeindicated, attempts to print columns of characters utilizing electroniccircuitry alone for locating and columnizing the print characters hasoften resulted in skewed columns, especially on long tape runs. Thepresent solution to the problem of skewed columns is considered to be amajor improvement as provided for by this particular invention. Further,the problem of useless or wasted carriage return time has now beeneliminated so that carriage motion in either direction is alwaysutilized for printing.

In regard to the combination of the mechanical locating mask (linearstrobe bar 60) and the inter-relating electronic circuitry to operatethe matrix print heads, the 32 slots of the slot sets 66,, and 68,,precisely locate the columns into which any given character is to beprinted, since the print heads will not be free to print unless theconditions of FIG. 3B are fulfilled such that the sensing devices ofchannel C are off, those of channel B are off, but those of channel Aare being strobed by the 32 slots of print field 71 and/or print field73. Thus, the 32 slots or apertures of the two print fields provide aset of precisely located positions which can be sensed by the electroniccircuitry, in regard to when and where it is permissible to print agiven character on the printout tape, should such a character be waitingin memory for printout.

A reversible motor moves the carriage and the matrix printer heads backand forth transverse the record or printout media, such as the audittrail and the receipt form as shown in FIG. 1. As the carriage so moves,the sensing devices, of course, move from their HOME slots.

As shown in FIG. 2, the sensing devices and the carriage 12 are alignedon the mid-HOME area. Depending upon the direction of travel, thecarriage and sensing devices will move either from the center mid-I-IOME toward the right or toward the left, and the carriage will moveuntil it comes to either the right HOME area or the left HOME area atwhich time the carriage will stop. Should there be more characters ofdata to be printed, of course the reversible motor and carriage willagain move to traverse the printing media in order to printout thenecessary information until such time as there is no more characterinformation to be processed for printing.

As was previously described in connection with FIGS. 3A and 38, as thecarriage leaves the HOME slot areas, the absence of a signal in thesensing devices of channel C and channel B and channel A indicates thebeginning of the print field, such as 71 or 73. As the carriage with itslight sensing means continues to move past the linear strobe bar 60, theuncovering of the first slot of 66,, then causes the light sensingsignal (known as the character strobe examples of which are shown inFIG. 38 as occurring in channel A) to initiate a series of short pulses,at and 80.

When the light sensors 106 and 106 (FIG. 2) are sensitized by the firstslot (print field) of the set 66,,

this initiates a character strobe as shown as element 80 in FIG. 5 (andalso FIG. 3B). Referring to FIG. 5A, the character strobe 80 isamplified and used to activate a column skew one-shot multivibrator 81which multivibrator has a pulse width of a selectable nature that isnormally made to be about one-half the width of the character strobepulse width. The column skew one-shot 81 performs the function ofpositioning the character to be printed in coordination with the timingof the remainder of the circuitry regardless of which direction theprint carriage is moving, that is to say, regardless of which edge ofthe particular slot is being uncovered; for example, the right edge ofthe slot 66,,, 68,, or the left edge.

In FIG. 5A, a basic oscillator 82 (D) is frequencydivided in half byOscillator 82' (D and again frequency divided to one-fourth thefrequency by Column Oscillator 83 (D Thus, Column Oscillator 83 may beused to pulse Up Counter 84 and Down Counter 85 at a counting rate of770 columns per second. The Up Counter 84 counts the character spacecolumns l-14 of FIG. 4 using the digital numbers to 13. The Down Countercounts in reverse from columns 14 to 1 (again using digital numbers13-0).

The pulse of the one-shot multivibrator 81 resets the oscillator (Ddesignated element 82', and also resets the column oscillator (D 83, thecolumn oscillator 83 having a pulse width equal (FIG. 6A) to twice thepulse width of the oscillator 82 (or one-half the frequency).

The output of the column oscillator 83 is connected to an up-counter 84and down-counter 85. Elements 84 and 85 are counters having two four-bitcolumn counters. The up-counter 84 and the down-counter 85 provide thefunction of counting the columns within a given character to be printed,but from different directions in order to permit printing to occurduring carriage motion in either direction, that is, right to left, orleft to right.

The outputs of the up and down counters are fed to a multiplexer 86which outputs a signal indicative of the nine columns of print which goto make up any individual character. As seen in FIG. A, the multiplexer86 receives input pulses from oscillator 82 (D This may be called the Atime and may be set at 1,540 pulses per second. Thus, multiplexer 86 ismade to provide an output of the up-count" alternated with an output ofthe down count.

The column skew one-shot multivibrator 81 also has an output which isconveyed to a print-head position up counter 87 which carries five-bitsof information. The five-bit output of this counter 87 corresponds tothe position information of the 32 character slots of the left and rightprint field 71 and 73: The up counter, 87 corresponds to the print headand carriage motion moving from left to right. A complementing circuit87,, alternately provides reverse character position counts whichcorrespond to the motion of the carriage and print head from right toleft. The output of the counter 87 which provides information as toprint-head position for each of the 32 character spaces is conveyed to acomparator 88. The comparator 88 is keyed to the A time (D 82' so thatit can alternately compare print head position counts in the up(left-right) direction and in the down (right-left) direction.

Simultaneous with these other units of information being provided to thecomparator 88 and the multiplexer 86, a fast clock oscillator 89 (havingapproximately 32 times the speed of the oscillator 82') provides anoutput conveyed to a buffer counter 90. The buffer counter is a five-bit(up) counter, and its output tells the sequence position of theparticular character residing at the output end of the circulating shiftregister 91.

It will be seen that the comparator 88 receives printhead position countinformation, and at the same time the comparator 88 receives from thebuffer counter 90, the count position location of characters in memoryto be printed. The comparator 88 thus compares the transverse positionof the print head with the buffer counter 90 information count which isrepresentative of a particular character and its character spaceposition count.

Concurrently, the oscillatory output of the fast clock oscillator 89 isused to operate a character buffer circulating shift register 91 whichconsists of a dynamic shift register having an output to a charactergenerator readonly memory 92. The character generator read-only memory92 has another input taken from the multiplexer 86 which is indicativeof the column position information of a given character to be printed.Thus, when there is a correlation and a compare between a charactercount in the circulating shift register 91 and the correct column countof a character (as indicated by the output of the multiplexer 86) thenthe output of the character generator 92 is dumped into the latchcircuit 93.

Referring to FIG. 5B, the remainder of the electronic control circuitryis shown in more detailed form. The latch circuit 93 of FIG. 5A is inreality composed of two latch circuits: an A latch 93,, and B latch 93,,as shown in FIG. 5B.

Referring again to FIG. 5B, it will be seen that the comparator 88 hasan output line to the A latch 93,, and to the B latch 93,,. Further, thecharacter generator ROM 92 has an output set of seven lines to the Alatch 93,, and to the B latch 93,,.

The output of the A latch 93,, is used to empower the seven hammers ofthe left matrix head while the output lines of the B latch 93,, comprisea series of lines which go to drive the seven hammers of the rightmatrix head.

Circuit 94,, (NAND gate and solenoid driver circuit) is shown connectedto one output line of B Latch 93,, and also connected to one line ofHammer Timing One- Shot Circuit 94,. This is exemplary in the drawing toindicate that each of the output lines of A Latch 93,, and B Latch 93,,are similarly provided with such gate circuits as exemplified by 94,.

Since the right matrix printhead (58 of FIG. 1) is required to print ontwo separate stations (stations 18 and 20 of FIG. 1) in an invertedprintout, the output lines of B Latch 93,, are passed through aninverting circuit 99 (FIG. 5B) which inverts the order of the printheaddriving signals from their normal order so that the right printhead 58,when positioned over station 18 (receipt station) will print itscharacter data in an upside down orientation as seen in FIG. 1 on recordmedium 36. The inverter 99 is only active when a control signal line 99,(activated by the right print field apertures 68,, of strobe bar 60 andcarriage locais printing on record medium 36.

As seen in FIG. A, there was provided enabling circuitry 94 in order tocontrol the operation of the matrix print heads. This system is shown inmore detail in FIG. 5B wherein there is provided a group of hammertiming one-shots 94,, which are used to phase the firing of the hammersof the left matrix head; and there is also provided another group ofhammer timing one-shots 94,, which are used to phase the timing of thehammer driving for the right matrix head.

As will be subsequently shown in the timing diagrams, the firing of theleft print head and the right print head is done on alternate cycleseven though they appear to be printing simultaneously due to the highrate of printing.

FIGS. 6A, 6B, and 6C are timing drawings illustrative of various timingcycles used by the electronic control circuitry of the printing system.These timing diagrams may be understood more completely by concurrentreference to the drawings and description of FIGS. 5A and 58 to whichthey also refer.

Referring to FIG. 6A, at line 6-1, there will be seen the basicoscillator (D) pulses which correspond to element 82 of FIG. 5A.

Line 6-2 shows the timing cycles involved in oscillator 82' (D whereinthe pulse frequency is divided in half in that oscillator D providesonly one output pulse during the time that the basic oscillator (D) isproviding two output pulses.

Line 63 shows the timing cycle provided by oscillator 83 (D whichfurther subdivide its on/off pulses into longer time periods. These timeperiods constitute A Time where the logic output is zero or false, and aB Time where the logic output is one or true.

Line 6-4 shows the On" time in this cycle that it is possible to triggerthe hammer-one-shot for the hammers of the left print head. Similarlyline 6-7 shows the phase B trigger hammer one-shot On time which can beused to trigger the print heads of the right print head.

Line 6-5 shows the time available for firing the hammers of the leftprint head through the enabling circuitry 94.

Line 6-6 shows basic reference timing markings in microseconds to givesome idea of the relative times involved.

Line 6-8 shows how a match can occur during the A Time in order to causea printout of the left print head; and likewise, line 6-9 shows how amatch from the comparator may occur in order to print out informationthrough the right-hand print head during B time.

Just below line 6-4 there is shown a time designation indicating thatone column of the character printing space has a time equivalent of1,280 microseconds and this is plotted on the'timing diagram in order toshow relative occurrence times.

The basic oscillator (D) shown at line 6-1 is shown to have a singlecycle time of 320 microseconds while the oscillator D has a cycle timeof 640 microseconds. The oscillator (D (at line 6-3) has a cycle time of1,280 microseconds and is the equivalent time for one column time. Thus,the time period for one column has been split into A Time and a B Timeas shown at line 6-3 which also correlates with the drawing of FIG. 4where there is shown a phase A time and a phase B time. Since the fastclock 89 runs at least 32 times greater than the basic oscillator D, or64 times greater than the A Time rate, then during the course of any oneparticular column print time, all 32 character spaces in memory(circulating shift register 91) are scanned for their position andcompared in the comparator 88 so that there will be at least two matchesoccurring every 320 microseconds which is one-half of the A timeavailable for printing on the left matrix print head. Likewise, thereare at least 32 character spaces in circulating register 91 which arescanned with the possibility of at least two matches occurring duringthe B Time or printout time for the right matrix print head.

Referring to FIG. 6B, there is shown a series of timing diagramsindicating relative relationships between the character strobe pulsesand other timing functions. In FIG. 6B, line 6-10, there is seen acharacter strobe pulse occurring (which is normally set at 55 pulses persecond). Line 6-11 shows the column skew one-shot 81 (as referred to inFIG. 5A), and as seen, the column skew one-shot pulse is approximatelyhalf the pulse width of the character strobe pulse but is initiated bythe leading edge of the character strobe pulse. Referring to FIG. 63, itwill be seen in line 6-(10) that the character strobe pulse, which isderived from a slit (66 68,, of FIG. 3A) in the strobe bar, has aleading edge which triggers the column skew one-shot as seen in line6-(11). The trailing edge of the column skew one-shot pulse, line6-(11), starts the column counter line 6-(12) so that th matrixprinthead may initiate its printout for each column of the characterspace.

While the carriage is moving in the left to right direction, thecharacter strobe is triggered by the left edge of the slit in the strobebar. However, if the carriage and printhead are moving in the oppositedirection, from right to left, then it is the right-hand edge of theslit of the strobe bar which triggers the character strobe and thecolumn skew one-shot pulse. Now since the slit in the strobe bar is of afinite width, and the left-hand edge of the slit is separated from theright-hand edge of the slit, then therefore it can be seen that thetriggering start pulse on the left to right motion is going to bedifferent position-wise from the triggering or start pulse when thecarriage is moving from right to left, since the left edge of the slitand the right edge of the slit in the strobe bar are separated by a gap.The effect of this would normally be to cause characters which wereprinted in left to right motion to be out of columnar alignment withcharacters which were printed while the carriage was moving in the otherdirection, from right to left.

Thus, by providing an adjustment for the column skew one-shot of FIG. 6Band line 6-(11) thereof (the adjustment is in the width of the columnskew oneshot), this adjustment has the effect of compensating for theprint solenoid lag time, the flight time of the wire styli, and thewidth of the strobe bar slit, so that when the character printout ismade in the left to right direction and then made in the right to leftdirection, a visual comparison can be made to see how well thecharacters in each line fall one under the other. Thus, the adjustmentof the width of the column skew oneshot pulse width can be done byvisually watching the printout columnar alignment as the printing occursin both directions.

As was seen in FIG. 5A, the output of the column skew one shot is usedto reset the basic oscillator D, the oscillator D the oscillator D andalso the up and down counters 84 and 85. Further, as was indicated inFIG. 4, the trailing edge of the output pulse of the Column skewone-shot 81 triggers the start of a character space. Also, the trailingedge of the pulse of the column skew one-shot resets and restarts thebasic oscillator D which is used to pulse the column counters 84 and 85.Referring to line 6-12, the start of the basic oscillator (D) triggersthe column counters 84 and 85 into pulses which are shown havingnumbered spaces between them. These numbered spaces between the 14pulses are the timing features which define the total character spacefor the printout and spacing of each individual character, and alsodefine each of the nine print and five no print columns of the characterspace shown in FIG. 4.

Line 6-13 of FIG. 6B shows the A Time timing pulses which have half thepulse-width but double the frequency of the pulses from the columncounter shown in line 6-12. The on portions of the A Time" pulses areone-half the pulse width of the column counter pulse width. The trailingedges of the A Time pulses trigger the phase A pulses of line 6-14 forenabling the firing of the left print head; the leading edges of the ATime pulses trigger the phase B pulses of line 6-15 to enable the firingof hammers in the right print head.

Lines 6-14 and 6-15 show the print hammer pulses in timing sequence forthe A print hammer and the B print hammer (left and right print headhammers) which are shown to operate alternately in slightly differentphases. The printer of this embodiment uses a carriage having dualprintheads, a left printhead and a right printhead (as one faces thefront of the keyboard of the terminal). A unique problem arises here inthat, as seen in FIG. 1, the left printhead will always be arranged towrite or print its characters in the printout orientation as shown onthe paper record 38 of the audit trail station 20. This means that aperson facing the front keyboard can directly read the characters sincethey are in the proper orientation for one facing the front of themachine. The last 20 lines of the transaction are visible to theoperator on the audit trail.

However, on the receipt station 18, and the record paper 36, it will beseen that the orientation of the character printout is reversed andinverted. The result is to produce a receipt oriented in standardaccounting form (top to bottom) for the customers receipt.

The dual type printhead carriage 12 operates to cover and to print outon any two of the three printout stations. When the carriage 12 is inthe position shown in FIG. 1, then the left-hand printhead 56 will beprinting with its orientation for a person standing in front of themachine, and the right-hand printhead 58 will be printing in the reverseinverted orientation.

Now, when the dual printhead carriage is moved to the left side of themachine, it will be seen that while the left-hand printhead 56 willstill be printing in the front orientation for an operator facing thekeyboard, however, the right-hand printhead 56 must be in a reversedcondition from what it had previously been in that it must now alsoprint in the front printout orientation for a person facing thekeyboard.

Thus, while the left-hand printhead 56 will always print in the sameorientation (the front orientation), the right-hand printhead 58 mustreverse itself when it is printing on the audit station 20. That is tosay, it must reverse and invert its printout from its printout as shownon the receipt station 18 on the paper record 36.

Thus, the situation involved here is not simply a case where oneprinthead is simply duplicating the other printhead, but rather is asituation in which the two printheads are separated in space and operateunder different conditions and have different output results at certaintimes.

Station 46, the forms station, prints in the front orientation and theform moves inwardly toward the machine to provide the proper orientationof the printout.

Referring to FIG. 6C, there is shown another group of timing diagramsrelative to the electronic control circuitry of the data terminalprinter.

Line C-l shows the output pulses of the fast clock 89 which are made torun at least 32 times greater than the basic oscillator frequency D.Line C-2 shows the output of the circulating shift register or buffer 91maintaining constant character information reading until the end of eachfast clock cycle after which there is an information change, but thecharacter information remains constant during the entirety of the fastclock cycle. This indicates that there is a period of approximately 10microseconds wherein the character information at the output ofcirculating shift register 91 is stable and useable.

Line C-3 of FIG. 6C shows how the the trailing edge of the fast clockpulses are used to trigger the buffer counter 90 in order to count thecharacter spaces in coordination with the character spaces in thecirculating shift register. The buffer counter 90 counts spaces from 0up to 31, then resets to 0 again.

Line C-4 shows the entry of the first character into the circulatingshift register 91 as being located in the number one position since theposition zero is not used but is a (spacing) position.

Line C-5 of FIG. 6C indicates that during the time of the firstcharacter position, there will be a match" as a result of the comparator88 which will set the latch unit 93 for a printout through one of theprint heads.

The fast clock 89 pulses the circulating shift register 91 so that, whenthe printhead is at any given position across the printing line, thecirculating shift register pulses more than 32 times during the columndwell time, so that at any given character space-column position, allcharacters in the circulating shift register are scanned.

Thus, when the comparator 88 detects that a match has occurred asbetween the buffer counter 90, the 5-bit up counter 87 (which counter 87provides information as to the printhead position for each of the 32character spaces), then the comparator 88 will trigger the A latch 93 sothat the character generator signals from character generator ROM 92 canoperate to cause the printhead to print the appropriate dot pattern forthe character column.

However, the character generator ROM 92 must be gated by the output ofthe multiplexer 86 which provides the appropriate character-column-codeto the character generator ROM 92 as to which particular orientation ofthe character to be printed.

Since we have an up-counter 84 and a down-counter 85, it does not makeany difference whether the printhead is moving from left to right orright to left. Since printing can take place in either direction, theup" counter 84 is used for printhead motion from left to right and thedown counter 85 is used for printhead motion from right to left.

The multiplexer 86 alternately switches between the up-count anddown-count column code in feeding character generator ROM 92 whenprinting is occurring on both the receipt station and audit stationsimultaneously. The use of either the up-count or the downcount isdetermined by the direction of printing motion. The control signal D tomultiplexer 86 selects the appropriate up or down counter code.

The complementing circuit 87,, takes the information of the 5-bit upcounter 87 and complements it so as to provide reverse characterposition counts which correspond to the motion of the carriage andprinthead from right to left.

The up-counter 87 corresponds to the printhead position where thecarriage is moving from left to right while the complementing circuit87, provides reverse character position counts of the printhead positioncorresponding to the motion of the carriage and print head from theright to the left side.

In essence, the subject printer eliminates the need for carriage returnsuch that the printer is always printing while moving in the right toleft direction or in the left to right direction. There is no loss orwasted time for the action of returning the carriage printhead to aninitial or beginning position, as is characteristic of the prior art.

Thus, the conditions for a printout are:

a. that the output character of the circulating shift register have acount--address (provided by buffer counter 90) which when supplied tothe Comparator 88, matches up with the count of the 5-bit up counter 87.The count of Counter 87 gives the position information of the 32character spaces of the left and right print fields 71 and 73;

b. that the given output character of circulating shift register 91 isfed into character generator ROM 92 and generator ROM 92 is supplied (bymultiplexer 86) the appropriate column code of the 14 columns of thecharacter space which is determined by the up-counter 84 or thedown-counter 85.

Thus, herein has been described a data terminal printing unit withelectronic control circuitry capable of accurate and positive printingon any one of three separate print stations or alternately on any two ofsaid print stations simultaneously.

The present set of printout stations have been described as a receiptstation, an audit-trail station, and a forms station. Any two of thesestations may be activated for simultaneous printing during anyparticular cycle of transaction activity; or if not necessary, the onlyprintout that is needed to take place will take place on the audit trailprintout station. Another feature of the present embodiment involves thefeature in which the printout on-the receipt station is printed out inupside down orientation to the printout at the audit trail and formsstation. This is easily accomplished by the use of inversion orcomplementing circuitry. Concurrently, with this feature of one printstation printing upside down to another print station, it should also benoted that the problem of column skewing has been resolved thereby andalso no longer occurs.

What is claimed is:

1. In a data terminal printer system providing for printout ofcharacters on a recording medium programmed for a series ofcharacter-spaces each of said character-spaces being programmed toconsist of m vertical columns of which n columns are used for characterprintout and (m-n) columns are provided for nonprint spacing, thecombination comprising:

a. a plurality of printout stations having separate recording media eachof which are separately movable;

b. carriage means movable transversely back and forth across saidprintout stations;

c. first and second dot matrix printheads mounted on said carriagemeans; said printheads including a plurality of wires for impacting onsaid recording media;

d. sensing means for determining the location of each of said printheadsrelative to each of said plurality of printout stations and relative toeach column of each unit character-space;

e. means for generating character strobe pulses indicative ofcharacter-spaces available for printing on each of said plurality ofprintout stations;

f. a circulating shift register for storage of character data to beprinted, said circulation rate being at least 32 times the rate of saidcharacter strobe pulses;

g. means for input of data characters into said circulating shiftregister;

h. means for providing a real-time count of each character-space locatedopposite the real-time location of said printhead during printheadmotion in either of two directions;

i. first counting means for providing information as to what particularcolumn of a character-space is available for printing by each of saidfirst and second matrix printheads;

j. multiplexing means to alternately provide a count of eachcharacter-space column during carriage motion for the left-rightdirection of motion and for the right-left direction of carriage motion;

k. second counting means for providing character position informationfrom said circulating shift register to said first and second matrixprintheads, said position information including data for left-rightcarriage motion and for right-left carriage motion;

1. comparison means for comparison of the printhead position count ofeach of said first and second matrix printheads with the count of eachcharacter position in said circulating shift register, said comparisonbeing responsive to the appropriate direction of carriage motion;

m. memory translation means for programming a selected character symbolinto signals representative of dots in a series of columns; and

n. circuit means, activated by said memory translation means, forempowering selected wires of said printhead as said printhead ispositioned at each column of a character-space, said circuit meansempowering said first and second printheads in alternate phases.

2. In a data terminal printer system providing for programmed printoutof data characters in a group of unit character spaces, each unitcharacter space having 14 vertical columns per character space of whichnine columns are used for character printout and five columns are usedfor non-print spacing, the combination comprising:

a. a plurality of printout stations having movable recording media;

b. carriage means movable transversely back and forth across saidprintout stations;

0. first and second wire matrix printheads mounted on said carriagemeans;

d. indicia means for programming the location of character-spacesavailable for printing on each recording media for each printoutstation;

e. sensing means for determining the carriage and printhead positionrelative to each of said character spaces available for printing;

f. means for input of data characters in a memory device;

g. means for addressing each of the data characters in said memorydevice; and

h. means for matching the programmed character space positions with theappropriate data character address positions in said memory deviceduring transverse motion of the printheads in either direction in orderto trigger the first and second printheads into a printout of the propercharacter in the proper character space on the preselected printoutstations desired.

3. The printer system of claim 2 including means for the alternatetriggering of the first and second printheads for printout during theperiod of any given column count which was started by the characterposition strobe derived from said indicia means.

4. The printer system of claim 2 including means for vertical columnaralignment of characters printed on one line of recording media withcharacters printed out on other lines of recording media.

5. The printer system of claim 2 including means for adjusting the timebetween the initiation of a character strobe pulse, which locates anavailable character space on the recording media, and the initiation ofa series of column count pulses, which pulses permit characterimprintation dots to be printed by said printheads.

6. In a printing device in which the printed characters are formed ofdifferential combinations of the dots of a matrix of dots arranged insequential columns, the combination comprising:

a. a plurality of printout stations each having separately movablerecording media;

b. carriage means movable transversely back and forth across each ofsaid print-.out stations;

c. first and second wire matrix printheads mounted on said carriagemeans and juxtaposed movably across said plurality of printout stations,said printheads being capable of printout while moving from left .toright or right to left;

d. means for programming character spaces on said printout stations;

e. sensing means for establishing the printhead positions relative toeach programmed character space;

f. means for intake and storage of character input data;

g. means for matching printhead position information with storedcharacter data location information in order to trigger the printout ofa stored character at a programmed location on one or more of therecording media of the plurality of printout stations;

h. initiating means for activating said first and second printheads intoprintout of a sequential series of columns of dots whether saidprintheads are moving from right to left or left to right.

7. The printing device of claim 6 including timing means for alternatelytriggering the printout times of the said first and second printheadsduring each period of column strobing of each character to be printed.

8. The printing device of claim 6 including adjustment means for saidinitiating means, said adjustment means providing for the verticalcolumnar alignment of printout characters on one line of the recordingmedia with the printed out characters on succeeding lines of therecording media.

9. The printing device of claim 6 including means for simultaneousprinting on two of said plurality of printout stations whereby theprintout from said second printhead is selectively controlled to printcharacters in a front orientation or a reverse orientation.

10. The printing device of claim 6 wherein said sensing means comprisesan indicia bar having indicia to indicate end-stop positions for saidprinthead and to indicate programmed character space positions as beingavailable for printout separately for each of two different positions ofsaid carriage means and including readout means to read said indiciafrom said indicia bar for conversion to electronic timing signals.

11. In a printing device in which the printed characters are formed ofdifferential combinations of the dots of a matrix of dots arranged insequential columns the combination comprising:

a. a printout station having movable recording media;

b. carriage means movable transversely back and forth across saidprintout station;

c. printhead means mounted on said carriage means, and capable ofprintout during carriage motion back and forth across said print-outstation;

d. sensing means for establishing the printhead position relative toeach character space programmed as available for printing on saidrecording media;

e. means for intake and storage of character input data;

f. means for matching printhead position information with storedcharacter data location information for printout of a stored characterat a designated location on the recording media, said means-for matchingbeing operative for causing character printout during forward or reversemotion of said carriage means.

12. The printing device of claim 11 including means for verticalcolumnar alignment of the printout of characters on one line of therecording media with the printout of characters on other lines of thesame recording media.

13. The printing device of claim 11 wherein said sensing means comprisesan indicia bar having selected indicia to indicate end stop positionsfor said printhead and to indicate character print positions programmedas available for printout on said recording media and including meansfor initiating the printout of a combination of dots in a column duringthe time that the printhead means is moving from left to right or ismoving from right to left; and including means for adjustment of saidinitiating means so that the printout of characters on one line of printof said recording media is properly aligned columnarly with the printoutof a column skew one-shot circuit triggered by the leading edge of saidcharacter strobe pulse and for providing a column-skew pulse;

column-counting circuitry for strobing the various columns of acharacter-space, said columncounting circuitry being triggered by thetrailing edge of said column-skew pulse.

15. The printing device of claim 14 wherein the column skew one-shotcircuit is adjustable in order to regulate the width of the column skewpulse.

1. In a data terminal printer system providing for printout ofcharacters on a recording medium programmed for a series ofcharacter-spaces each of said character-spaces being programmed toconsist of m vertical columns of which n columns are used for characterprintout and (m-n) columns are provided for non-print spacing, thecombination comprising: a. a plurality of printout stations havingseparate recording media each of which are separately movable; b.carriage means movable transversely back and forth across said printoutstations; c. first and second dot matrix printheads mounted on saidcarriage means; said printheads including a plurality of wires forimpacting on said recording media; d. sensing means for determining thelocation of each of said printheads relative to each of said pluralityof printout stations and relative to each column of each unitcharacterspace; e. means for generating character strobe pulsesindicative of character-spaces available for printing on each of saidplurality of printout stations; f. a circulating shift register forstorage of character data to be printed, said circulation rate being atleast 32 times the rate of said character strobe pulses; g. means forinput of data characters into said circulating shift register; h. meansfor providing a real-time count of each character-space located oppositethe real-time locatiOn of said printhead during printhead motion ineither of two directions; i. first counting means for providinginformation as to what particular column of a character-space isavailable for printing by each of said first and second matrixprintheads; j. multiplexing means to alternately provide a count of eachcharacter-space column during carriage motion for the leftrightdirection of motion and for the right-left direction of carriage motion;k. second counting means for providing character position informationfrom said circulating shift register to said first and second matrixprintheads, said position information including data for left-rightcarriage motion and for rightleft carriage motion;
 1. comparison meansfor comparison of the printhead position count of each of said first andsecond matrix printheads with the count of each character position insaid circulating shift register, said comparison being responsive to theappropriate direction of carriage motion; m. memory translation meansfor programming a selected character symbol into signals representativeof dots in a series of columns; and n. circuit means, activated by saidmemory translation means, for empowering selected wires of saidprinthead as said printhead is positioned at each column of acharacter-space, said circuit means empowering said first and secondprintheads in alternate phases.
 2. In a data terminal printer systemproviding for programmed printout of data characters in a group of unitcharacter spaces, each unit character space having 14 vertical columnsper character space of which nine columns are used for characterprintout and five columns are used for non-print spacing, thecombination comprising: a. a plurality of printout stations havingmovable recording media; b. carriage means movable transversely back andforth across said printout stations; c. first and second wire matrixprintheads mounted on said carriage means; d. indicia means forprogramming the location of character-spaces available for printing oneach recording media for each printout station; e. sensing means fordetermining the carriage and printhead position relative to each of saidcharacter spaces available for printing; f. means for input of datacharacters in a memory device; g. means for addressing each of the datacharacters in said memory device; and h. means for matching theprogrammed character space positions with the appropriate data characteraddress positions in said memory device during transverse motion of theprintheads in either direction in order to trigger the first and secondprintheads into a printout of the proper character in the propercharacter space on the preselected printout stations desired.
 3. Theprinter system of claim 2 including means for the alternate triggeringof the first and second printheads for printout during the period of anygiven column count which was started by the character position strobederived from said indicia means.
 4. The printer system of claim 2including means for vertical columnar alignment of characters printed onone line of recording media with characters printed out on other linesof recording media.
 5. The printer system of claim 2 including means foradjusting the time between the initiation of a character strobe pulse,which locates an available character space on the recording media, andthe initiation of a series of column count pulses, which pulses permitcharacter imprintation dots to be printed by said printheads.
 6. In aprinting device in which the printed characters are formed ofdifferential combinations of the dots of a matrix of dots arranged insequential columns, the combination comprising: a. a plurality ofprintout stations each having separately movable recording media; b.carriage means movable transversely back and forth across each of saidprint-out stations; c. first and second wire matrix printheads mountedon saId carriage means and juxtaposed movably across said plurality ofprintout stations, said printheads being capable of printout whilemoving from left to right or right to left; d. means for programmingcharacter spaces on said printout stations; e. sensing means forestablishing the printhead positions relative to each programmedcharacter space; f. means for intake and storage of character inputdata; g. means for matching printhead position information with storedcharacter data location information in order to trigger the printout ofa stored character at a programmed location on one or more of therecording media of the plurality of printout stations; h. initiatingmeans for activating said first and second printheads into printout of asequential series of columns of dots whether said printheads are movingfrom right to left or left to right.
 7. The printing device of claim 6including timing means for alternately triggering the printout times ofthe said first and second printheads during each period of columnstrobing of each character to be printed.
 8. The printing device ofclaim 6 including adjustment means for said initiating means, saidadjustment means providing for the vertical columnar alignment ofprintout characters on one line of the recording media with the printedout characters on succeeding lines of the recording media.
 9. Theprinting device of claim 6 including means for simultaneous printing ontwo of said plurality of printout stations whereby the printout fromsaid second printhead is selectively controlled to print characters in afront orientation or a reverse orientation.
 10. The printing device ofclaim 6 wherein said sensing means comprises an indicia bar havingindicia to indicate end-stop positions for said printhead and toindicate programmed character space positions as being available forprintout separately for each of two different positions of said carriagemeans and including readout means to read said indicia from said indiciabar for conversion to electronic timing signals.
 11. In a printingdevice in which the printed characters are formed of differentialcombinations of the dots of a matrix of dots arranged in sequentialcolumns the combination comprising: a. a printout station having movablerecording media; b. carriage means movable transversely back and forthacross said printout station; c. printhead means mounted on saidcarriage means, and capable of printout during carriage motion back andforth across said print-out station; d. sensing means for establishingthe printhead position relative to each character space programmed asavailable for printing on said recording media; e. means for intake andstorage of character input data; f. means for matching printheadposition information with stored character data location information forprintout of a stored character at a designated location on the recordingmedia, said means for matching being operative for causing characterprintout during forward or reverse motion of said carriage means. 12.The printing device of claim 11 including means for vertical columnaralignment of the printout of characters on one line of the recordingmedia with the printout of characters on other lines of the samerecording media.
 13. The printing device of claim 11 wherein saidsensing means comprises an indicia bar having selected indicia toindicate end stop positions for said printhead and to indicate characterprint positions programmed as available for printout on said recordingmedia and including means for initiating the printout of a combinationof dots in a column during the time that the printhead means is movingfrom left to right or is moving from right to left; and including meansfor adjustment of said initiating means so that the printout ofcharacters on one line of print of said recording media is properlyaligned columnarly with the printout of characters on succeeding linesof print of saId recording media.
 14. The printing device of claim 13wherein said initiating means includes: an indicia bar having slittedapertures for programming positions of available character-spacepositions available for printout along said recording media; movablelight and photodetector sensing means referenced to said printheadposition for scanning said slitted apertures and for providing acharacter strobe pulse; a column skew one-shot circuit triggered by theleading edge of said character strobe pulse and for providing acolumn-skew pulse; column-counting circuitry for strobing the variouscolumns of a character-space, said column-counting circuitry beingtriggered by the trailing edge of said column-skew pulse.
 15. Theprinting device of claim 14 wherein the column skew one-shot circuit isadjustable in order to regulate the width of the column skew pulse.